Polyvinyl chloride resin composition having excellent impact resistance and weatherability

ABSTRACT

A POLYVINYL CHLORIDE RESIN COMPOSITION HAVING EXCELLENT IMPACE RESISTANCE AND WEATHERABILITY CAN BE OBTAINED BY BLENDING 100 PARTS BY WEIGHT OF A VINYL CHLORIDE POLYMER WITH 5 TO 80 PARTS BY WEIGHT OF A RESIN WHICH COMPRISES 20 TO 80 PARTS BY WEIGHT OF A CORE-CRUST STRUCTURAL CROSSLINKED POLYTALKYL ACRYLATE ELASTOMER (A) AND 80 TO 20 PARTS BY WEIGHT OF A POLYMER (B) OBTAINED BY POLYMERIZATION OF A VINYL MONOMER OR A MIXTURE THEREOF, AT LEAST A PART OF THE MONOMER FOR A POLYMER (B) BEING GRAFTPOLYMERIZED IN THE PRESENCE OF ELASTOMER (A), ELASTOMER (A) BEING OBTAINED BY THE STEPS OF DISSOLVING AN ORGANIC PEROXIDE HAVING A DECOMPOSITION TEMPERATURE HIGHER THAN 60*C. IN A MONOMER COMPRISING 80 TO 100% BY WEIGHT OF AT LEAST ONE ALKYL ACRYLATE WHOSE ALKYL GROUP HAS 1 TO 10 CARBON ATOMS AND 0 TO 20% BY WEIGHT OF A VINYL MONOMER, POLYMERIZING SAID MONOMER IN AN AQUEOUS SOLUTION CONTAINING A WATER SOLUBLE REDOX INITIATOR AND AN EMULSIFIER AT A TEMPERATURE LOWER THAN THE DECOMPOSITION TEMPERATURE OF SAID ORGANIC PEROXIDE TO OBTAIN AN ELASTOMER LATEX, HEATING AND STIRRING SAID ELASTOMER LATEX AT A TEMPERATURE HIGHER THAN THE DECOMPOSITION TEMPERATURE OF SAID ORGANIC PERIOXIDE TO OBTAIN A CROSSLINKED ELASTOMER LATEX ADDING TO A LATEX CONTAINING 100 PARTS BY WEIGHT OF SAID CROSSLINKED ELASTOMER 30 TO 150 PARTS BY WEIGHT OF A MONOMER WHICH COMPRISES 80 TO 100% BY WEIGHT OF AT LEAST ONE ALKYL ACRYLATE WHOSE ALKYL GROUP HAS 1 TO 10 CARBON ATOMS AND 0 TO 20% BH WEIGHT OF A VINYL MONOMER AND IN WHICH AN ORGANIC PEROXIDE HAVING A DECOMPOSITION TEMPERATURE HIGHER THAN 60*C. IS DISSOLVED, SEED POLYMERIZING THE MONOMER WITH A WATER SOLUBLE REDOX INITIATOR AT A TEMPERATURE LOWER THAN 60*C. IN THE PRESENCE OF SAID LATEX CONTAINING CROSSLINKED ELASTOMER AND HEATING THE THUS OBTAINED LATEX TO A TEMPERATURE HIGHER THAN 60*C.

United States Patent O US. Cl. 260-876 R 11 Claims ABSTRACT OF THEDISCLOSURE A polyvinyl chloride resin composition having excellentimpact resistance and weatherability can be obtained by blending 100parts by weight of a vinyl chloride polymer with 5 to 80 parts by weightof a resin which comprises 20 to 80 parts by weight of a core-cruststructural crosslinked polyalkyl acrylate elastomer (A) and 80 to 20parts by weight of a polymer (B) obtained by polymerization of a vinylmonomer or a mixture thereof, at least a part of the monomer for apolymer (B) being graftpolymerized in the presence of clastomer (A),elastomer (A) being obtained by the steps of dissolving an organicperoxide having a decomposition temperature higher than 60 C. in amonomer comprising 80 to 100% by Weight of at least one alkyl acrylatewhose alkyl group has 1 to carbon atoms and 0 to by weight of a vinylmonomer, polymerizing said monomer in an aqueous solution containing awater soluble redox initiator and an emulsifier at a temperature lowerthan the decomposition temperature of said organic peroxide to obtain anelastomer latex, heating and stirring said elastomer latex at atemperature higher than the decomposition temperature of said Organicperioxide to obtain a crosslinked elastomer latex, adding to a latexcontaining 100 parts by weight of said crosslinked elastomer to 150parts by weight of a monomer which comprises 80 to 100% by weight of atleast one alkyl acrylate whose alkyl group has 1 to 10 carbon atoms and0 to 20% by weight of a vinyl monomer and in which an organic peroxidehaving a decomposition temperature higher than 60 C. is dissolved, seedpolymerizing the monomer with a water soluble redox initiator at atemperature lower than 60 C. in the presence of said latex containingcrosslinked elastomer and heating the thus obtained latex to atemperature higher than 60 C.

This invention relates to a resin composition mainly comprising apolyvinyl chloride resin and having excellent impact resistance andweatherability.

Polyvinyl chloride resin is widely used because of its low price andexcellent physical and chemical properties, but it is somewhat inferiorin impact resistance, heat resistance and cold resistance.

There are methods for improving said drawbacks. For example, the impactresistance of polyvinyl chloride resin ice is improved by blending arubbery elastomer or an impact resistant resin having the rubberyelastomer as a substrate. According to the typical example of suchmethods, a resin obtained by graft-polymerizing styrene, acrylonitrileor methyl methacrylate onto a diene elastomer, such asacrylonitrile-butadiene-styrene resin (hereinafter referred to as ABSresin) or methyl methacrylate-butadiene-styrene resin (hereinafterreferred to as MBS resin) is blended with vinyl chloride resin.

The composition obtained by such method is extremely improved in itsimpact resistance and cold resistance, but has a substantialdisadvantage of poor weatherability because the elastomer containsdouble bond. In order to improve the weatherability, it has beenproposed to substitute a saturated elastomer containing no double bondfor said diene clastomer. However, no saturated elastomer has been foundwhich has enough compatibility with polyvinyl chloride resin and whichexhibits the same impact resistance as in case of using the dieneelastomer. For example, as an elastomer vinyl acetate-ethylene copolymeror chlorinated polyethylene has been used for obtaining an impactresistant polyvinyl chloride resin composition having goodweatherability. However, the impact resistance of the thus obtainedpolyvinyl chloride resin composition is not satisfactory and furthermoremechanical and thermal properties which are intrinsic to polyvinylchloride resins are reduced.

When acrylic ester elastomers obtained by the usually knownpolymerization method are used, little improvement is attained in impactresistance and moreover molding processability of the composition ismarkedly reduced. This is because polyacrylic esters obtained by theusual polymerization method have crosslinked structure with difiicultyand hence are apt to deform when subjected to physical changes of heat,pressure, etc., whereby orientation and strain are caused at molding.

We have made researches on production of a polyvinyl chloride resincomposition having excellent weatherability and impact resistance when asaturated elastomer is used as an elastomer component. As the result, wehave found a method for producing a core-crust structural crosslinkedpolyalkyl acrylate elastomer which is a kind of saturated elastomer and,by using that core-crust structural crosslinked elastomer, we havesucceeded in producing a composition which has excellent weatherabilityas well as impact resistance which equals to that of a composition whichis obtained by using a diene elastomer.

This invention relates to a vinyl chloride resin composition havingexcellent impact resistance and weatherability, which is obtainedbyblending 100 parts by weight of a vinyl chloride polymer with 5 toparts by weight of a resin which comprises 20 to 80 parts by weight ofcore-crust structural crosslinked polyalkyl acrylate elastomer (A) and80 to 20 parts by weight of a polymer (B) obtained by polymerization ofa vinyl monomer or a mixture thereof, at least a part of the monomer forthe polymer (B) being graft-polymerized in the presence of elastomer(A), which is obtained by the steps of dissolving an organic peroxidehaving a decomposition temperature higher than 60 C. in a monomercomprising 80 to by Weight of at least one alkyl acrylate whose alkylgroup has i to 10 carbon atoms and to 20% by weight of a vinyl monomer,polymerizing said monomer in an aqueous solution containing a watersoluble redox initiator and an emulsifier at a temperature lower than 60C. to obtain an elastomer latex, heating and stirring the thus obtainedlatex at a temperature higher than 60 C. to obtain a crosslinkedelastomer latex, adding to a latex containing 100 parts by weight of thecrosslinked elastomer 30 to 150 parts by weight of a monomer whichcomprises 80 to 100% by weight of at least one alkyl acrylate, whosealkyl group has 1 to 10 carbon atoms and 0 to 20% by weight of a vinylmonomer and in which an organic peroxide having a decompositiontemperature higher than 60C. is dissolved, seed-polymerizing the monomerusing a water soluble redox initiator at a temperature lower than 60 C.in the presence of said latex containing the crosslinked elastomer andfurther heating the thus obtained latex to a temperature higher than 60C.

The polyvinyl chloride resin compositions of the invention preferablycomprise a mixture of 100 parts by weight of a vinyl chloride polymerand to 80 parts by weight of a resin (I); said resin comprising:

(a) 20 to 80 parts by weight of a core-crust structural crosslinkedpolyalkyl acrylate elastomer (A) and (b) 80 to 20 parts by weight of apolymer (B) obtained by the polymerization of at least one vinyl monomerselected from the group consisting of vinyl mononuclear aromatichydrocarbons selected from the group consisting of styrene and a-methylstyrene; vinyl cyanides selected from the group consisting ofacrylonitrile and methacrylonitrile; lower alkyl acrylates selected fromthe group consisting of methyl methacrylate, ethylmethacrylate,propylmethacrylate, and butylmethacrylate; lower alkyl vinyl ethersselected from the group consisting of methylvinyl ether, ethylvinylether, propylvinyl ether and butylvinyl ether; and lower alkyl vinylketones selected from the group consisting of methylvinyl ketone,ethylvinyl ketone, propylvinyl ketone and butylvinyl ketone, at least apart of said vinyl monomen being graft-polymerized in the presence ofsaid elastomer (A); said elastomer (A) being prepared by the steps of:

(1) Providing a vinyl monomer having dissolved therein an organicperoxide having a decomposition temperature higher than 60 C., saidvinyl monomer comprising:

(a) 80 to 100% by weight of at least one alkyl acrylate, the alkyl groupof which having 1 to carbon atoms, and

(b) 0 to by weight of a second vinyl monomer selected from the groupconsisting of vinyl mononuclear aromatic hydrocarbons selected from thegroup consisting of styrene and a-methyl styrene; vinyl cyanidesselected from the group consisting of acrylonitrile andmethacrylonitrile; lower alkyl acrylates selected from the groupconsisting of methyl methacrylate, ethylmethacrylate,propylmethacrylate, and butylmethacrylate; lower alkyl vinyl ethersselected from the group consisting of methylvinyl ether, ethylvinylether, propylvinyl ether and butylvinyl ether; and lower alkyl vinylketones selected from the group consisting of methylvinyl ketone,ethylvinyl ketone, propylvinyl ketone and butylvinyl ketone;

(2) Polymerizing said vinyl monomer at a temperature below 60 C. in anaqueous solution containing a water soluble redox initiator to obtain anelastomer latex;

(3) Heating and stirring said latex at a temperature higher than 60 C.to obtain a crosslinked elastomer latex corresponding to the coreportion of said elastomer (A);

(4) Adding to a latex, containing 100 parts by weight of saidcrosslinked elastomer, 30 to 150 parts by weight of a vinyl monomerhaving dissolved therein an organic peroxide having a decompositiontemperature of higher than 60 C.; said vinyl monomer comprising:

(a) to by weight of at least one alkyl acrylate, the alkyl group ofwhich has 1 to 10 carbon atoms, and (b) 0 to 20% of said second vinylmonomer;

(5 Seed polymerizing said vinyl monomer with a water soluble redoxinitiator at a temperature below 60 C.; and

(6) Heating the resulting latex to a temperature above 60 0., therebysurrounding the core portion of the elastomer with a crust portion andforming the core-crust structural crosslinked polyalkyl acrylateelastomer (A).

By the term core-crust structural crosslinked polyalkyl acrylateelastomer is meant an elastomer obtained by adding a monomer mainlycomposed of an acrylic ester to a crosslinked acrylate elastomer whichconstitutes a core, seed-polymerizing the monomer and furthermorecrosslinking the thus obtained elastomer.

Said core-crust structural crosslinked polyalkyl acrylate elastomer issynthesized as follows.

0.1 to 5% by weight of an organic peroxide (e.g.,

benzoyl peroxide) having a decomposition temperature higher than 60 C.is dissolved in a monomer composed of more than 80% by weight of anacrylic ester and less than 20% by weight of a vinyl monomer. The thusobtained mixture is added to an aqueous solution containing anemulsifier and a water soluble redox initiator (e.g., potassiumpersulfate-sodium bisulfite) and the mixture is emulsion-polymerized ata temperature lower than 60 0., preferably 35 to 45 C. The monomer ispolymerized in several hours, but said organic peroxide is hardlydecomposed and is homogeneously distributed in polymer particles. Then,thus obtained latex is stirred with heating at a temperature higher than60 C., preferably higher than 70 C. to cause crosslinking in particlestate of the elastomer. To the thus obtained latex containing 100 partsby weight of the crosslinked elastomer is added 30 to parts by weight ofa monomer composed of or mainly composed of an acrylic ester in which0.1 to 5% by weight of an organic peroxide is dissolved. Thus obtainedmixture is emulsion polymerized without addition of further emulsifierand with addition of an aqueous solution containing water soluble redoxinitiator at a temperature lower than 60 C., preferably 35 to 45 C. Themonomer is polymerized in several hours, but the organic peroxide ishardly decomposed and homogeneously distributed in polymer particles.Thus obtained latex is stirred with heating to a temperature higher than60 C. to cause crosslinking, thereby to obtain a core-crust structuralcrosslinked polyalkyl acrylate elastomer (A). Better result is obtainedwhen the inside part (core) of the elastomer (A) is harder than theoutside part (crust) thereof.

Illustrative of the vinyl monomer copolymerized with the acrylic estersare vinyl aromatic hydrocarbons, vinyl cyanides, alkyl methacrylates,vinyl ethers, vinyl ketones, etc.

The organic peroxides which may be used for crosslinking are required tomeet the following conditions.

(1) They have a decomposition temperature higher than (2) They aresoluble in said acrylic ester monomers, but

insoluble in water.

(3) They are difiiculty subjected to rapid induced decomposition withpropagation polymer radical.

Examples of the organic peroxides which meet the above conditions arelauroyl peroxides, octanoyl peroxides, cyclohexanone peroxide, benzoylperoxide, pchl orobenzoyl peroxide, dicumyl peroxide, di-tertiary butylperoxide, etc.

The redox initiators used in polymerization are required to be watersoluble and not to be oil soluble. Especially such a reducing agent thataccelerates the decomposition of the peroxide in the monomer is notsuitable. Preferable redox initiators include potassiumpersulfate-sodium bisulfite, potassium persulfate-sodium thiosulfate,ammonium persulfate-sodium bisulfite, etc.

To thus obtained core-crust structural crosslinked polyalkyl acrylateelastomer (A) latex, are added one or more vinyl monomers which providea hard and brittle resin upon polymerization, radical polymerizationinitiator and a chain transfer, and the added monomers are polymerizedin one step or two steps to obtain a graft copolymer.

Furthermore, the thus obtained graft copolymer and a polymer obtained byindependently polymerizing said one or more vinyl monomers with additionof a radical polymerization initiator and a chain transfer may be mixed(for example, in latex form) to obtain desired graft-blend type resin.

In both cases of the graft copolymer and the graft-blend type resin, thecontent of the elastomer is required to be 20 to 80% by weight.

As the vinyl monomers used, there are, for example, vinyl aromatichydrocarbons, vinyl cyanides, alkyl methacrylates, vinyl ethers, 'vinylketones, etc.

The vinyl chloride polymers which are one component of the compositionof this invention are vinyl chloride polymer or copolymers mainlycomposed of vinyl chloride having a mean degree of polymerization of 500to 2,000, preferably of 700 to 1,500 or those which are chlorinatedafterwards.

Any means such as hot roll, Banbury mixer, or extruder which are usedfor attaining homogeneous mixing may be used for mixing the graftcopolymer or graftblend type copolymer with the vinyl chloride polymer.At this time, the usually employed stabilizers, antioxidants,lubricants, fillers, pigments, etc. may be added optionally.

The thus obtained composition of this invention has excellentcharacteristics such as high impact resistance and weatherability and,therefore, may be successfully used even as working materials in such afield that usual polyvinyl chloride cannot be used. Furthermore, thecomposition of this invention is superior to the conventional impactresistant polyvinyl chloride compositions in weatherability and hencemay be used outdoors. For example, they are suitable as raw materialsfor pipes, construction materials, etc.

The following examples are given by way of specifically illustratingthis invention and are not intended to be construed as limiting in anysense. In these examples, percentages and parts are given by weight.

In accordance with the above compositions, firstly, BPO was dissolved inthe monomers. Thus obtained mixture was added to an aqueous solutioncontaining emulsifier (sodium lauryl sulfate), KPS, and NaHSO and themonomers were polymerized with stirring under a nitrogen atmosphere at40 C. for 4 hours. Thereafter, the thus obtained solution was stirredand heated to 90 C. for 4 hours to obtain a core portion of elastomer(A-l) latex, which had been crosslinked in a latex state.

Preparation of a core-crust structural crosslinked elastomer (A-l) PartsA-1 latex (as solid) 50 n-Butyl acrylate 50 BPO 0.75 KPS 0.15 NaHSO 0.15Deionized water 100 In the same manner as the case of preparation of theA-l) polymerization was carried out with KPS-NaHSO initiator at 40 C.for 4 hours without further adding emulsifier, and furthermorecrosslinking was effected with BPO by heating at C. for 4 hours. Thethus obtained core-crust structural crosslinked polyalkyl acrylate (A-l)had a gel content of and a swelling index in toluene of 7.2.

Preparation of graft copolymer (G-l) Parts A-l latex (as solid) 40Styrene 24 Cumene hydroperoxide 0.072 Dextrose 0.4 Sodium pyrophosphate0.2 Sodium soap of rosin 0.8 Ferrous sulfate 0.002 Deionized water 40 Amixture having the above components was graft copolymerized at 60 C. for4 hours. After completion of the polymerization, the followingcomposition was added to the product and the mixture was graftcopolymerized at 60 C. for 4 hours.

After completion of the reaction, the reaction product was coagulated indilute sulfuric acid and washed with water and dried to obtain powderygraft copolymer. 15 parts of said graft copolymer, parts of polyvinylchloride resin TK1000 manufactured by Shinetsu Kagaku Co., Ltd.), 3parts of dibutyl tin maleate, 1 part of barium stearate and 0.5 part ofstearic acid were blended by Henschel mixer and then the mixture wasextruded by an extruder into a sheet, which was kept at C. and 200kg./cm. for 10 minutes and then pressure molded. The properties of thethus molded product were as follows:

Sharpy impact strength 65.5 kg.-cm./cm. Tensile strength --492 kg./cm.Vicat softening point -84.6 C.

Measured according to ASTM D256-56 (test piece: 90 x 15 x 5 mm.,V-notched, depth 2 mm.).

Measured according to ASTM D63,858T (1 mm. in thickness) at 20 C. at arate of 5 cm./m1n.

Measured according to ASTM D1525-58T (test piece of 3 mm. in thickness).

EXAMPLES 2-10 Compositions as shown in Table 1 were obtained in the samemanner as in Example 1.

As is clear from Table 1, the compositions using an elastomer havingcore-crust structure are extremely superior to those shown incomparative Example '1 using an elastomer having no core-crust structurein impact resistance. Furthermore, as shown in comparative Examples 2-4,no effects are attained unless Whe'n imparting corecrust structure, bothcrust and core are crosslinked as in this invention.

Furthermore, it is clear that the composition of this invention hasexcellent impact resistance without reducing tensile strength andlowering softening point of vinyl chloride resin as compared to the caseof using chlorinated polyethylene or vinyl acetate-ethylene-vinylchloride grafted copolymer.

TABLE 1 Elastorner part Core part Crust part Modifier Resin part partsto Sharpy Vicat BPO BPO PV impact softenpercent percent 1st stage 2ndstage resin strength Tensile g Ex, Monomer comono- Monomer comonomonomermonomer 1 (kg.cm./ strength point No. No. composition mer compositionmer composition composition parts cmfl) (kg/omfl) C.)

-1 BuAlMMA=17l3 1.5 B11A=20 1.5 st=24 MMAIAN=24I12 15 55.5 492 84.6i-z--- BuA/MMA=17/3 1.5 2EHA=20 1.5 s1=24 MMAIAN=24I12 15 68.5 487 85.0=17 a 1.5 2EHA=20 1.5 St=24 MMA/AN=24/12 15 57.2 491 84.7 III m4---2EHAlMMA=17l3 1.5 BuA=20 1.5 st=24 MMAIAN=24I12 15 57.8 479 84.3BuA/MMA=17/3 1.5 BuA=20 1.5 AN/St=l5/45 15 25.7 4.88 84.5 BuA/MMA=17/31.5 BuA=20 1.5 s 24 15 4 15 486 84.3 BuA/MMAnm 1.5 BuA=20 1.5MMAIAN=40I20 15 21.5 495 84.6 =17/3 1.5 BuA=20 1.5 St=24 MMAIAN=24I12 611.2 532 84.0 "I 5-1--- BuA/MMA=17/3 1.5 BuA=20 1.5 81:24 MMA/AN=24/12 15,5 515 SM B A/MMA=l7/3 1.5 BuA=20 1.5 sc=24 MMAIAN=24I12 20 so 468 84.71 l m/o 1.5 St=24 MMA/AN=24/12 8.7 482 84.5 21 AB uA/MMA-JM/fi 1.5 BuA=0 St=24 MMAAN=24I12 15 9.2 485 84.5 1 AB6 uA/MMA=34/6 0 BuA=20 1 5 St=24MMA/AN=24/l2 15 6.5 483 84.3 41" xB-7 BuAlMMA=34l6 0 BuA=20 0 sr;24MMAIAN=24I12 15 5.2 4.88 84.2

5 Polyvinyl chloride resin 555 1 43 I1 lane-Vin lohlorlde raft copolymer15 11-8 411 82.2 6 Vmylacetate t y Y 8 15 24.0 402 810 7 Chlorinatedpolyethylene (01 content, wt. percent) 1 Comparative.N0'rE.-BuA=n-butylaerylate; AN=acrylonitrile; 2EHA=2-ethyl- EXAMPLES11-12 Preparation of graft copolymer (G-1) Parts A-l latex (as solid) 70Styrene 12 Cumene hydroperoxide 0.036 Dextrose 0.20 Sodium pyrophosphate0.10 Sodium soap of rosin 0.40 Ferrous sulfate 0.001 Deionized water 20The above composition was graft copolymerized at 60 C. for 4 hours.After completion of the reaction, the following composition was added tothe above copolymer and the mixture was graft copolymerized at 60 C. for4 hours The above composition was polymerized at 60 C. for 3 hours.After completion of the reaction, the following composition was .addedto thus obtained polymer and the mixture was graft copolymerized at 60C. for 3 hours to obtain a copolymer for blend.

Parts Methyl methacrylate Acrylonitrile 20 t-Dodecyl mercaptan 0.24Cumene hydroperoxide 0.18 Dextrose 1.0 Sodium pyrophosphate 0.5 Sodiumsoap of rosin 1.8 ,Ferrous sulfate p 0.005 Deionized water -2 90hexylacrylate; St=styrene; MMA=methyl methacrylate; BPO=benzoylperoxide.

Preparation of graft-blend type copolymer parts of G-l latex and 75parts of C-1 latex were homogeneously mixed in latex form. The mixturewas coagulated in dilute sulfuric acid and washed with water and driedto obtain powdery graft-blend type copolymer (GB-1).

Similarly, 100 parts of G-1 latex and 100 parts of C-1 latex wereblended to obtain GB-2.

Preparation of resin composition 15 parts of the graft-blend typecopolymer, 100 parts of polyvinyl chloride, 3 parts of dibutyl tinmaleate, 1 part of barium stearate and 0.5 part of stearic acid wereblended in Henschel mixer. Thus obtained blend was extruded into asheet, which was kept at C. under 200 kg./cm. for 10 minutes to pressuremold the sheet. The properties of the pressure-molded sheet are shown inTable 2.

EXAMPLES 13-14 Preparation of graft copolymer (G-2) Parts A-l latex (assolid) 70 Styrene 21 Acrylonitrile 9 Cumene hydroperoxide 0.036 Dextrose0.20 Sodium pyrophosphate 0.10 Sodium soap of rosin 0.40 Ferrous sulfate0.001 Deionized water 20 The above composition was graft copolymerizedat 60 C. for 4 hours to obtain a graft copolymer (G-2).

Preparation of resin (C-2) for blend The above composition waspolymerized at 60 C. for 3 hours to obtain a copolymer (C-2) for blend.

Preparation of graft blend type copolymer 100 parts of G-2 latex and 75parts of C-2 latex were homogeneously mixed in latex form. The mixturewas coagulated in diluted sulfuric acid and washed with water and driedto obtain powdery graft-blend type copolymer (GB-3).

Similarly, 100 parts of G-2 latex and 100 parts of C-2 10 (1) providinga vinyl monomer having dissolved therein an organic peroxide having adecomposition temperature higher than 60 C., said vinyl monomercomprising:

latex were blended to obtain GB-4 using GB-3 or 613-4; (a) 80 to 100% byweight of at least one resin compositions were prepared as in Example11. The alkyl acrylate, the alkyl group of which properties thereof areas shown in Table 2. having 1 to carbon atoms, and

, ABM] 2 (b) 0 to 20% by weight of a second vlnyl monomer selected fromthe group consist- Example gfg g gg fif $321 1? zg jg 10 ing of vinylmononuclear aromatic hydro- Number copolymer kg.-cm./cm. kg./cm. point,0. carbons selected from the group consisting 5 490 8&7 of styrene anda-methyl styrene; vinyl cya- 25.7 510 85.2 nides selected from the groupconsisting of gig gg gig acrylonitrile and methacrylonitrile; loweralkyl acrylates selected from the group con- The graft-blend typecopolymer is preferable because sisting of methyl methacfylate,ethylmeth' the values of the properties of the compositions causedacfylate, p py y f, and y by the elastomer (A) can be freely changed byfreely methacrylate; lower alkyl Y ethers changing the elastomer contentwith change of amount of lefited from the P COIlSlStlllg of hy the ftresin vinyl ether, ethylvmyl ether, propylvinyl EXAMPLE 15 ether andbutylvinyl ether; and lower alkyl vinyl ketones selected from the groupcon- Accelerated weathering test was carried out on the sisting ofmethylvinyl ketone, ethylvinyl resin compositions obtained in Examples1, 2, 7, 11 to k t l i l k t d b t l i l measure Sharpy impact strength.The test of weatherk ability was also carried out. For comparisons, theresults (2) l i i id i l monomer at a of the composition obtained using15 parts of vinyl aceper-ature b l 60 C i an aque uS l itate'ethylene-vinyl chloride graft P Y chlorinated containing a watersoluble redox initiator to 0bpolyethylene, or MBS resin and the resultof polyvinyl mi ane1astomel-1atex; chloride resin alone are also shownin Table 3. (3) heating d stirring id latex at a temperas f In Tables 1,n e compositions of ture higher than C. to obtain a crosslinked thislnventlon have nearly the Same eXcelleIlt impact elastomer latexcorresponding to the core portion resistance, thermal properties,processability, tensile f id e1astomer (A); strength, etc. ascompositions comprising PVC resin to (4) adding to a l containing 100parts b which, for example, MBS resin was blended, and have 5 weight ofsaid crosslinked elastomer, 30 to 150 extremely superior weatherabilityto said compositions.

parts by weight of a vinyl monomer having TABLE 3.WEATHERABILITY (TOYORIKA CO. LTD. IN JAPAN WE-2 TYPE WEATHEROMETER) Sharpy impact strength(kg.-em./cm.

100 hrs. 200 500 1, 000 Original exposure hrs. hrs. hrs. Note Example 165. 5 65. 0 57. 6 60. 5 25. 8 Example 2 68. 5 65. 6 64. 6 57. 5 52. 8Example 7 21. 5 21. 5 20. 7 19. 6 18. 8 glxample t1}- -E "lug 53.51 51.8 51. 0 46. 5

ompara ve xamp e 3. 1 3.1 3. 0 Polyvinyl chloride resin. Comparat veExample 6- 11.8 10. 5 10. 0 9. 4 7. 8 Vinyl aeetate-ethylene-vinylchloride. Comparative Example 7- 24. 0 21. 5 20. 6 16. 2 15. 0Chlorinated polyethylene. Comparative Example 8 51.2 15. 5 4. 5 3. 0 2,8 M33 r i What is claimed is: 0 1. A polyvinyl chloride resincomposition which comprises a mixture of 100 parts by weight of a vinylchloride polymer and 5 to 80 parts by weight of a resin (1); said resincomprising (a) 20 to 80 parts by weight of a core-crust structuralcrosslinked polyalkyl acrylate elastomer (A) and (b) 80 to 20 parts byweight of a polymer (B) obtained by the polymerization of at least onevinyl monomer selected from the group consisting of vinyl mononucleararomatic hydrocarbons selected from dissolved therein an oragnicperoxide having a decomposition temperature of higher than 60 C.; saidvinyl monomer comprising:

(a) 80 to 100% by weight of at least one alkyl acrylate, the alkyl groupof which has 1 to 10 carbon atoms, and

(b) 0 to 20% of said second vinyl monomer;

(5) seed polymerizing said vinyl monomer with a water soluble redoxinitiator at a temperature below 60 C.; and

60 (6) heating the resulting latex to a temperature i group conslstmg ofStyrene and Styrene; above 60 C., thereby surrounding the core porvmylselected from thefigioup consisting of tion of the elastomer with acrust portion and acrylomtrtle and methacrylonitrile; lower alkylforming the core crust stru m I k d acrylates selected from the groupconsisting of meth- 1 1k 1 l l c m cross e yl methacrylate,ethylmethacrylate, propylmethacry- PO ya y acry ate 6 astomer 2. A resincomposition according to claim 1, wherein said resin (1) is obtained bypolymerizing all of the monomer for the polymer (B) in the presence ofthe elastomer (A).

3. A resin composition according to claim 1, wherein said resin (1) isobtained by mixing a graft polymer (b) obtained by polymerizing a partof monomer for the polymer (B) in the presence of the elastomer (A) witha polymer (C) separately prepared by polymerizing the remaining part ofmonomer for the polymer (B) in such a manlate, and butylmethacrylate;lower alkyl vinyl ethers selected from the group consisting ofmethylvinyl ether, ethylvinyl ether, propylvinyl ether and butylvinylether; and lower alkyl vinyl ketones selected from the group consistingof methylvinyl ketone, ethylvinyl ketone, propylvinyl ketone andbutylvinyl ketone, at least a part of said vinyl monomer beinggraft-polymerized in the presence of said elastomer (A); said elastomer(A) being prepared by the steps of:

1 1 ner that the total amount of the polymer (B) component is 80 to 20parts by weight of the resin (I).

4. A resin composition according to claim 1, wherein said resin (I) isprepared by polymerizing a part of monomer for the polymer (B) in thepresence of the elastomer (A) to prepare a graft polymer (b), and thenadding and polymerizing the remaining part of monomer for the polymer(B) in the presence of the graft polymer (b).

5. A resin composition according to claim 1, wherein saidresin (I) isprepared by polymerizing a part of monomer for the polymer (B) in thepresence of the elastomer (A) to prepare a graft polymer (b), adding andpolymerizing a part of the remaining monomer for the polymer (B) in thepresence of the graft polymer (b) to obtain a graft polymer and thenblending the graft polymer (c) with a polymer prepared by separatelypolymerizing the remaining monomer for the polymer (B).

6. A resin composition according to claim 1, wherein the elastomer (A)is composed of 100 parts by weight of core portion which comprises 80 to100% by weight of nbutyl acrylate and 0 to 20% by weight of methylmethacrylate and 30 to 150 parts by weight of crust portion whichcomprises n-butyl acrylate, and the monomer for the polymer (B) containsat least one member selected from methyl methacrylate, styrene andacrylonitrile.

7. A resin composition according to claim 1, wherein the monomer for theelastomer (A) comprises a monomer which comprises 80 to 100% by Weightof at least one member selected from n-butyl acrylate and 2-ethylhexylacrylate and 0 to 20% by weight of methyl methacrylate.

8. A resin composition according to claim 1, wherein the oragnicperoxide is benzoyl peroxide and the amount thereof is 0.3 to 3.0% byweight based on the weight of the monomer for the elastomer (A).

9. A resin composition according to claim 1, wherein the organicperoxide is selected from the group consisting of lauroyl peroxide,octanoyl peroxide, cyclohexanone peroxide, benzoyl peroxide,p-chlorobenzoyl peroxide, dicumyl peroxide, and di-tertiary butylperoxide.

10. A resin composition according to claim 1, wherein the redox catalystused is selected from the groupcon rinated copolymers mainly composed ofvinyl chloride,

and has a mean degree of polymerization of 500 to 2,000.

References Cited UNITED STATES PATENTS 3,426,101 2/ 1969 Ryan et a1.260-876 3,562,235 2/1971 Ryan 260876 X 3,502,604 3/1970 Nakatsuka et al.260885 X FOREIGN PATENTS 1,117,124 6/1968 Great Britain 260885 MURRAYTILLMAN, Primary Examiner H. W. ROBERTS, Assistant Examiner US. Cl. XR

26029.6 RB, MQ, 881, 885

